The central objective of the proposed research is to continue gathering information on psychophysiologic and psychoendocrine aspects of sexual function in normal subjects and in patients suffering from sexual dysfunctions. The rationale of the study is to obtain normative data on sex-related physiologic changes during sleep in subjects free from sexual problems with the aim of applying these findings to the study of patients with sexual disorders. Psychophysiologic studies of men with erectile disorders continue to be few, but there is already enough evidence that the assessment of nocturnal penile tumescence provides valuable information on the nature of some erectile problems. It is proposed that the concurrent assessment of nocturnal penile tumescence and pituitary-gonadal secretory patterns during sleep provides a valuable model for the investigation of male sexual function and dysfunction. Studies are plaaned to conduct sequential determinations of blood LH, FSH and testosterone in normals and in men with erectile disorders of psychological origin and to relate variations in hormonal levels to stages of sleep and penile tumescence. The existence of subgroups of men with psychogenic impotence which may differ in the pattern of nocturnal penile tumescence or in pituitary-gonadal function will be explored. Studies concerning the psychophysiology of female sexuality will focus on the gathering of normative data on vaginal blood flow changes during exposure to sexually arousing stimuli and in relation to stages of sleep. The assessment of endocrine and penile tumescence changes in males with erectile disorders of psychogenic origin may have diagnostic, as well as prognostic value. Similarly, the development and application of method for the measurement of vaginal blood flow during sexual arousal and sleep may provide basic information of significance to the study of sexual disorders.